UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE. 

AGRICULTURAL  EXPERIMENT  STATION. 


A  New  Method  oi  Making  Dry  Red  Wine. 


By  FREDERIC  T.  BIOLETTL 


BULLETIN    No.    177. 

(Berkeley,  Cal.,  February,  1906.) 


W.  W.  SHANNON 


SACRAMENTO: 

:     :     :     superintendent   state   printing. 
1906. 


BENJAMIN   IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist.     (Absent  on  leave.) 

E-  J.  WICKSON,  M.A.,  Acting  Director  and  Horticulturist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  CE-,  Irrigation  Engineer. 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.     {Soils  and  Alkali.). 

M.  E-  JAFFA,  M.S.,  Assistant  Chemist.     (Eoods,  Nutrition.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.     (Cereals,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.     (Fruits,  Waters,  Insecticides.) 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian  and  Bacteriologist . 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

RALPH  E-  SMITH,  B.S.,  Plant  Pathologist . 

E.  H.  TWIGHT,  B.Sc,  Diplome  E.A.M.,  Viticulturist. 

F.  T.  BIOIvETTI,  M.S.,  Viticulturist. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Entomologist  and  Asst.  Supt.  Farmers'  Institutes. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  of  Fertilizer  Control. 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist . 
ALBERT  M.  WEST,  B.S.,  Assistant  Plant  Pathologist. 

E-  H.  SMITH,  M.S.,  Assistant  Plant  Pathologist. 

G.  R.  STEWART,  Student  Assistant  in  Station  Laboratory . 
ALICE  R.  THOMPSON,  B.S.,  Assistant  in  Soil  Laboratory. 

D.  L.  BUNNELL,  Clerk  to  the  Director. 


R.  E-  MANSELL.  Foreman  of  Central  Station  Grounds. 

JOHN  TUOHY,  Patron,      ) 

>      Tulare  Substation,  Tulare. 
J.  FORRER,  Foreman,         ) 

J.  W.  MILLS,  Pomona,  in  charge  Cooperative  Experi ments  in  Southern  California . 

J.  W.  ROPER,  Patron, 

HENRY  WIGHTMAN,  In  cht 

ROY  JONES,  Patron,  f 

>      University  Forestry  Station,  Santa  Monica. 
J.  H.  BARBER,  Foreman,       ) 

VINCENT  J.  HUNTLEY,  Foreman  of  California  Poultry  Experiment  Station,  Petaluma. 


\      University  Forestry  Station,  Chieo. 
'large,      ) 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, zv ill  be  sent  to  any  citizen  of  tJie  State  on  application. 


A  NEW  METHOD  OE  MAKING  DRY  RED  WINE. 


In  Bulletin  No.  167  of  this  Station,  discussing  various  means  of 
improving  the  quality  of  dry  wines  made  in  hot  countries,  the  conclu- 
sion was  reached  that  the  method  which  offered  the  best  hope  of  attain- 
ing the  end  in  view  was  that  by  which  the  requisite  tannin  and  color  were 
extracted  by  heat  before  fermentation.  The  method,  as  outlined  there, 
is  as  follows: 

"1.  Heating  the  crushed  grapes  to  a  temperature  and  for  a  time 
sufficient  to  extract  the  necessary  color,  tannin,  and  body. 

"2.  Immediate  separation  of  the  must,  and  cooling  to  85°  F. 

u3.  Immediate  fermentation  of  the  must  at  a  temperature  not  exceed- 
ing 90°  F." 

The  bulletin  further  states:  "The  present  status  of  the  method  is 
this : 

"  1.  It  has  been  shown,  both  in  California  and  in  France,  that  it  is 
possible,  when  working  with  small  quantities,  to  attain  the  object  in 
view  by  this  method. 

"2.  The  method  has  been  used  with  success  in  France  in  the  whole 
output  of  a  cellar  manufacturing  75,000  gallons  of  wine  in  a  season.'' 

Experiments,  made  on  a  sufficiently  large  scale  during  the  past 
vintage,  have  further  demonstrated  that  the  method  is  perfectly 
adapted  to  large-scale  practice  in  California,  and  that  it  is  possible  by 
this  means  to  produce  a  wine  of  excellent  quality  where  it  had  been 
found  impracticable  to  do  so  by  the  old  methods.  These  experiments 
indicate  strongly,  moreover,  that  it  is  not  only  possible  to  make  good 
dry  red  wine  by  this  means,  but  that,  where  the  climate  is  hot  during 
the  vintage,  it  is  the  simplest  and  most  economical  method  of  attaining 
the  end  in  view  when  working  on  a  large  industrial  scale. 

This  is  not  intended  to  mean  that  the  use  of  this  method  alone  is  all 
that  is  necessary  to  improve  the  quality  of  the  dry  wines  of  our  hotter 
regions,  but  that,  together  with  proper  attention  to  the  ordinary  details 
of  wine-making,  the  proper  use  of  cooling  machines,  and  perhaps  of 
pure  yeast,  we  have  a  means  by  which  we  can  be  sure  every  year  of 
making  the  best  wine  that  the  grapes  available  are  capable  of  produc- 
ing. In  a  cellar  properly  arranged  for  the  purpose,  all  this  can  be 
accomplished  at  a  cost  so  little  in  excess  of  the  cost  of  the  usual  methods 
of  manufacture  that  the  loss  which  occurs  in  practically  every  large 


4  UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 

winery  in  the  State,  of  a  few  vats  of  wine  by  bad  or  incomplete  fermen- 
ation,  far  more  than  counterbalances  it. 

The  experiments  show  further  that,  where  the  grapes  are  well  ripened 
and  in  fair  condition,  all  that  is  necessary  in  our  hot  valleys,  for  the 
production  of  good,  sound  wine,  is  the  use  of  cooling  devices  in  the 
fermentation,  and  attention  to  proper  sterilization  of  vats  and  casks. 

In  order  to  give  a  clearer  idea  of  how  the  method  could  be  carried 
out  on  a  large  scale  in  a  winery  built  for  the  purpose,  a  plan  of  such  a 
winery  has  been  given  with  enough  detail  to  exemplify  all  parts  of  the 
process  and  to  enable  any  one  to  calculate  the  cost  of  operation. 

While  the  main  object  of  the  experiments  was  to  test  the  capabilities 
of  the  method  referred  to,  other  methods  and  other  matters  of  interest 
in  the  fermentation  of  wine  were  investigated  both  for  comparison  and 
for  the  purpose  of  devising  the  best  way  of  carrying  out  the  method  in 
practice. 

The  main  lines  of  investigation  were  the  following: 

1.  Extraction  of  color  and  tannin  by  artificial  heating. 

2.  Control  of  the  temperature  of  fermentation  by  means  of  a  cooling 
machine. 

3.  The  use  of  pure  and  selected  yeast. 

4.  The  use  of  sulfurous  acid  in  controlling  the  temperature  of  fer- 
menting grapes. 

5.  The  making  of  wine  from  incompletely  ripe  grapes. 

In  order  to  make  the  bearing  of  the  experiments  clear,  a  detailed 
account  of  the  method  used  is  necessary.  Reference  to  pages  19  to  26 
of  Bulletin  No.  167  will  make  the  objects  of  the  principal  experiment 
clear.  There,  will  be  found  a  discussion  of  the  effects  of  high  tempera- 
tures on  the  fermentation  of  wine,  and  an  account  of  the  preliminary 
laboratory  experiments  which  led  to  the  devising  of  the  method  used 
in  the  larger  Avinery  experiments  this  year. 

It  will  be  seen,  from  the  reference  given,  that  high  temperatures  have 
beneficial  and  necessary,  as  well  as  injurious,  effects  in  the  production  of 
dry  red  wine,  and  the  experiments  detailed  in  this  bulletin  show  that  a 
practical  method  has  been  devised  which  will  "combine  the  beneficial 
effects  of  heat  in  the  extraction  of  color,  tannin,  and  body  with  those 
of  cool  fermentation  in  producing  bouquet,  freshness,  and  maximum 
amount  of  alcohol."  These  experiments  also  indicate  very  strongly 
that  by  use  of  the  method  recommended  we  are  certain  to  produce  a 
sound  wine  from  any  grapes  in  fair  condition,  however  hot  the  season; 
and  that,  even  when  the  grapes  are  inferior  by  reason  of  mold,  drying 
up,  etc.,  much  better  wine  can  be  made  than  by  any  of  the  usual 
methods. 

The  principal  merit  of  the  method,  therefore,  is  the  certainty  it  gives 
that  every  rat  of  wine  will  be  perfectly  sound  every  year. 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE.  D 

DESCRIPTION    OF    METHOD. 

Crushing. — The  grapes  were  taken  as  they  came  to  the  winery  in  the 
usual  way,  passed  through  the  ordinary  crusher  and  stemmer,  and 
pumped  by  means  of  a  must-pump  through  the  regular  must-line  into 
1,500-gallon  vats. 

As  the  crushed  grapes  came  into  the  vat  a  small  amount  of  potassium 
meta-bisulfite  dissolved  in  water  was  added  gradually,  in  such  a  way  as 
to  distribute  it  equally  throughout  the  vat.  The  amount  i  ised  varied 
from  .2  to  .4  per  mil.  of  the  weight  of  the  grapes,  that  is  1o  say,  from 
6  to  12  ounces  per  ton. 

The  sulfite  was  added  to  paralyze  temporarily  the  action  of  the 
molds,  bacteria,  and  yeast  present,  and  to  facilitate  the  solution  of  the 
color.  Another  important  use  of  the  sulfite  is  to  prevent  too  much 
oxidation  during  the  heating,  and  so  to  avoid  the  "  rancido  "  taste  which 
might  be  acquired  if  the  grapes  were  allowed  to  remain  hot  too  long  or 
if  they  were  heated  too  high. 

Preparation  of  Vats. — The  vats  were  cleaned  with  hot  water  and 
soda  and  then  swabbed  with  a  3%  solution  of  commercial  sulfuric 
acid  to  partially  disinfect  them.  The  acid  solution  was  left  on  the 
walls  of  the  vats  for  a  few  hours  and  then  rinsed  off  with  water. 

Straining. — At  the  bottom  of  each  vat  was  placed  a  strainer  extend- 
ing from  the  bunghole  across  the  whole  bottom  to  the  opposite  side- 
The  form  of  strainer  used    is    shown  in    Fig.    1.     It   consisted   of   an 


G 


FIG.  1.    Strainer  for  bottom  of  Fermenting  Vat. 

inverted  rectangular  trough  closed  at  one  end  and  having  a  top  consist- 
ing of  a  solid  board,  and  sides  consisting  of  slats  made  with  beveled 
edges  like  the  slats  of  a  press  basket. 

These  strainers  were  found  to  be  not  sufficiently  effective,  owing  to 
the  very  thorough  way  in  which  the  grapes  were  broken  up  by  the 
method  of  handling.  In  practice  it  would  be  necessary  to  have  a  more 
efficient  method  of  straining,  or  to  adopt  a  method  of  crushing  the 
grapes  and  conveying  them  to  the  vats,  which  would  not  result  in  such 
complete  maceration. 

The  former,  i.  e.,  the  use  of  a  more  efficient  straining  device,  would 
be  preferable,  as  it  is  very  desirable  to  have  the  grape-pulp  thoroughly 
disintegrated  in  order  to  facilitate  the  extraction,  which  takes  place  the 
more  rapidly  the  more  completely  the  grapes  are  crushed. 


6  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

As  soon  as  the  vat  was  full  of  crushed  grapes  the  must  was  allowed 
to  run  off  the  skins  into  another  vat.  It  was  found  possible  to  run  off 
a  volume  of  must  equal  to  only  one  half  of  the  total  volume  of  the 
crushed  grapes.  With  a  better  arrangement  for  straining,  a  volume 
equal  to  two-thirds  could  be  run  off,  which  would  much  facilitate  the 
subsequent  operations. 

Heating. — As  soon  as  the  must  was  separated  it  was  passed  through 
the  heater  and  back  into  the  vat  containing  the  strained  skins.  The 
must  was  heated  to  from  140°  to  150°  F.,  and  as  the  grapes  were  much 
cooler  thev  remained  at  the  bottom,  and  it  was  found  verv  difficult  to 
mix  the  two  when  the  hot  must  was  pumped  on  to  the  top.  This  diffi- 
culty was  overcome  in  great  measure  by  attaching  the  hose,  bringing  the 
must  from  the  heater,  to  a  faucet  in  the  bottom  of  the  vat.  By  this 
means  the  hot  must  was  forced  through  the  cool  grapes,  and  a  thorough 
stirring  at  the  end  equalized  the  temperature  in  the  whole  vat. 

The  Heater. — The  must  was  heated  by  means  of  a  "  must-heater ': 
constructed  by  Gomot,  of  Nimes,  France.  This  machine  is  essentially 
a  large  tubular  pasteurizer,  the  exterior  of  which  is  shown  in  the  figure 
on  the  cover. 

The  height  of  the  boiler  is  6  feet  10  inches  from  the  ground  to  the 
top,  and  the  chimney  is  2  feet  5  inches  more.  Its  diameter  is  4  feet 
3-j  inches,  and  the  tube  connections  protrude  a  few  inches  more  on  all 
sides. 

It  consists  of  a  system  of  copper  tubes,  through  which  the  wine  runs, 
and  a  boiler  surrounding  them,  which  is  heated  by  a  fire  in  the  firebox 
below,  from  which  the  heat  passes  by  four  flues  into  the  chimney. 
When  used  in  the  way  intended  by  the  manufacturer,  the  boiler  is  filled 
with  water.  In  our  experiments,  acting  on  the  suggestion  of  Mr. 
Meakin,  Ave  found  it  more  convenient  to  simply  admit  steam  into  the 
boiler  and  to  dispense  with  both  water  and  fire. 

There  are  eighty  straight  copper  tubes  joined  by  unions  outside  the 
boiler,  as  shown  in  the  figure.  These  tubes  are  each  3  feet  10  inches 
long  and  1^  inches  in  diameter,  and  are  easily  cleaned  by  removing  the 
couplings,  for  which  purpose  the  arrangement  is  very  simple.  In  our 
experiments,  there  was  no  deposit  whatever  in  the  tubes,  and  after  pass- 
ing water  through  the  machine  they  were  found  perfectly  clean. 

The  machine  is  furnished  with  a  strainer,  which  prevents  seeds  and 
skins  passing  into  the  tubes.  This  strainer  must  be  opened  and  cleaned 
occasionally,  and  is  so  constructed  that  this  is  easily  done.  Four  ther- 
mometers are  placed  in  various  parts  of  the  heater,  which  enable  the 
operator  to  control  the  heating  perfectly.  There  is  one  thermometer  in 
the  boiler,  one  at  the  entrance  of  the  must,  one  at  the  exit,  and  one  half- 
way between  these.     By  carefully  watching  these  thermometers  and 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE.  7 

manipulating  the  steam  valve,  the  heating  can  be  regulated  in  a  few 
minutes  to  any  degree  required.  The  heating  remains  very  constant 
so  long  as  the  steam  pressure  does  not  vary,  and  providing  the  supply 
of  must  is  regular. 

A  hand  pump  can  not  be  used  to  supply  the  must,  as  the  output  is 
too  irregular.  It  is  necessary  to  have  a  pump  that  will  give  a  constant 
stream  of  uniform  volume.  For  this  purpose  a  steam  pump  would  be 
excellent,  as  its  output  can  be  regulated  to  any  desired  rate.  For  the 
experiments  a  gasoline  motor  pump  especially  constructed  by  Gomot 
for  the  purpose  was  used.     The  rate  of  pumping  could  be  varied  by  a 


FIG.  2.    Gomot  Motor  Pump. 


simple  arrangement  to  from  375  to  1,500  gallons  per  hour.  Such  control 
of  the  rate  of  pumping  is  necessary,  as  the  heating  depends  on  the  rate 
with  which  the  must  passes  through  the  machine,  as  well  as  upon  the 
amount  and  pressure  of  the  steam  admitted. 

Capacity  of  Heater. — It  was  found  that  the  machine  would  heat  1,000 
gallons  of  must  per  hour  from  75°  to  150°  F.  when  the  temperature  of 
the  boiler  was  kept  at  185°  F.  The  steam  pressure  during  the  trials 
was  80  pounds.  There  was  no  pressure  in  the  boiler  of  the  heater,  as  it 
has  an  opening  above. 

Heating  the  must  to  150°  F.  is  about  what  would  be  found  convenient 
in  practice  if  the  temperature  of  the  crushed  grapes  was  75°  F.  and  two- 


8 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


thirds  of  their  volume  of  must  was  passed  through  the  heater  at  150°  F. 
This  is  just  about  what  is  necessary  to  give  the  desired  results. 

Extraction. — When  the  mass  of  crushed  grapes  has  reached  the  desired 
temperature,  it  is  left,  with  occasional  stirrings  (every  three  or  four 
hours),  until  the  required  color  and  tannin  have  been  extracted  by  the 
must. 

It  has  been  shown  by  the  experiments  detailed  on  page  22  of  Bulletin 
No.  167  that  the  color  and  tannin  are  extracted  pari  passu,  so  that  by 
periodical  observations  of  the  color  it  is  possible  to  note  the  progress  of 
extraction. 

Salleron's  Vino-Colorimeter. — For  this  purpose  a  Salleron  vino-color- 
imeter is  extremely  useful.  A  very  full  description  of  the  nature  and 
use  of  this  instrument  was  given  by  Prof.   E.  W.  Hilgard  in   the  Viti- 


FIG.  3.    Salleron's  Vino-Colorimeter. 

cultural  Report  for  the  seasons  1885  and  1886,  on  pages  23  and  26.  So 
far,  this  is  the  best  and  most  practical  means  which  has  come  into 
general  use  for  measuring  the  color  of  wine,  and  as  some  quick  and 
reliable  means  of  determining  the  color  during  the  process  of  extraction 
is  necessary  for  the  proper  carrying  out  of  this  method,  a  short  descrip- 
tion of  the  instrument  is  given  here. 

The  colors  of  wines  differ  in  two  respects.  They  may  differ  in  tint  (that 
is  to  say,  the  kind  or  nature  of  the  color  may  differ),  and  they  may 
differ  in  intensity  (that  is,  the  depth  or  amount  of  color  may  differ). 
In  order,  therefore,  to  measure  the  color  of  a  wine  and  to  compare  it 
with  the  color  of  another  wine  we  must  measure  both  its  tint  and  its 
intensity.  Both  these  measurements  may  be  made  with  the  Salleron 
vino-colorimeter. 

For  the  determination  of  the  tint  a  scale  (Fig.  3,  G-H)  is  furnished, 
consisting  of  a  piece  of  cardboard  on  which  are  gummed  small  disks  of 
silk  which  represent  all  the  tints  usually  found  in  dry  red  wines.  At 
the  top  of  the  scale  is  a  disk  marked  VR  (violet-red),  which  is  the  tint 
of  a  new  wine  made  from  a  good  coloring  grape  with  full  acidity,  such 
as  the  Petite  Sirah  or  Cabernet.     At  the  bottom  of  the  scale  is  a  disk 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE. 


9 


VINOCOLOFilttLTME 


,1 


a 

\ 

A 

i^^«  i               —  * 

;  1MES»                        — 

El   — 

'   H                                   BL7*«I 

£  B Or- 

1 

3H- —                                       S^",,■ 

^  — 

B 


VK 


W 


V.RV 


VR 


YR 


( 


marked  3R  (third  red),  which  is  the  tint  of  an  inferior  coloring  grape 
with  low  acidity,  such  as  Grenache  or  Mission.  Between  these  extremes 
are  eight  other  disks  representing  the  intermediate  tints  which  red 
wines  may  have.  Altogether  there  are  ten  disks  repre- 
senting ten  tints,  which  are  marked  as  indicated  in  Fig.  4. 
Each  tint  differs  from  the  one  above  it  in  having  a 
slightly  greater  admixture  of  yellow. 

Wines  of  claret  type  should  not  fall  below  the  5V  R . 
while  those  of  Burgundy  type  may  go  to  the  bottom  of 
the  scale.  Ports  contain  more  yellow  even  than  the  3R, 
and  can  not  be  measured  satisfactorily  by  this  scale. 
As  wines  become  older  the  tint  gradually  becomes  yel- 
lower, so  that  a  wine  which  when  made  corresponds  to  the 
VR  disk  may  fall  to  the  5VR  disk  when  it  is  a  year  old. 
All  the  disks  are  made  with  the  same  intensity  of 
color,  «o  that  in  order  to  compare  wines  with  them  it  is 

necessary  to  re- 
duce the  inten- 
sity of  color  of 
the  wines  to  that 
of  the  disks. 
This  is  done  by 
varying  the 
thickness  of 
wine  throng  h 
which  we  look. 
If  we  observe 
the  color  of  a 
wine  by  looking 
through  it  in  a 
glass  three  inches  in  diameter 
it  will  appear  to  be  twice  as 
dark  or  intense  as  if  wre  look 
through  it  in  a  glass  of  only 
one  and  one-half  inches  diam- 
eter. This  principle  is  made 
use  of,  both  to  bring  the  wine 
to  the  standard  intensity  which 
makes  it  possible  to  compare  its 
tint,   and   also   to   measure  the 

FIG.  5.    Construction  of  Salleron's  Vino-Colorimeter.  ^ 

To  use  the  instrument  a  small 
portion  of  the  wine  is  placed  in  the  receptacle  V  (Fig.  5),  and  the  screw 
cap  ab  moved  up  or  down  until  the  thickness  of  wine  between  the  glass 


R  v 


J.SALIfRON 


FIG.  4. 
Scale  of  Tints. 


10  UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 

« 

disks  c  and  d  through  which  we  look  gives  us  an  intensity  equal  to 
that  of  the  disks.  The  scale  is  then  moved  back  and  fortli  until  the 
proper  tint  is  found. 

We  now  have  all  the  data  for  describing  the  exact  color  of  the  wine. 
The  tint  is  given  by  the  name  of  the  disk  used  and  the  intensity  by  the 
distance  of  d  from  c,  which  is  read  off  from  the  scale  on  the  outside  of 
the  eap  ab  at  the  point  marked  on  AB  with  an  arrow. 

If  we  get  such  a  reading  as  3VR,  160  it  means  that  the  tint  of  the 
wine  is  third  violet  red  and  the  standard  intensity  is  obtained  by  looking 
througli  160  hundredths  of  a  millimeter  of  the  wine.  If  we  get  the 
reading  80  on  the  scale  it  will  show  that  only  half  as  much  wine  is 
necessary  to  give  the  standard  intensity  and,  therefore,  that  the  wine 
is  twice  as  dark  or  intensely  colored  as  in  the  first  case.  The  smaller 
the  reading  on  the  scale,  therefore,  the  more  deeply  colored  the  wine. 

To  overcome  this  inconvenience  Professor  Hilgard  has  adopted  a  scale 
of  which  the  notation  is  inversely  proportionate  to  the  thickness  of  the 
wine  necessary  to  give  the  standard  tint,  and  of  which,  therefore,  the 
numbers  given  are  directly  proportionate  to  the  intensity  of  color.  For 
this  purpose  he  has  taken  a  wine  which  required  40  hundredths  of  a 
millimeter  to  give  the  standard  intensity  as  an  arbitrary  standard, 
which  he  calls  100.  A  wine  with  half  this  amount  of  color  would  then, 
with  this  scale,  have  an  intensity  of  50.  The  number  is  obtained  by 
dividing  4,000  by  the  reading  of  the  scale.  This  would  give  us,  then, 
for  the  first  example  an  intensity  of  4000~:-160,  or  25,  and  for  the 
second  4000^80,  or  50. 

If  R  represents  the  reading  on  the  scale,  then  4000  -f-R  =  Intensity 
by  Professor  Hilgard's  scale. 

Comparison  of  Scales. 
Salleron  Scale.  Hilgard  Scale. 

40  =  100 

80  50 

160  =  25,  etc. 

The  Hilgard  scale  has  the  great  advantage  of  giving  a  clear  idea  of  the 
intensity  of  color  in  a  wine  without  the  need  of  making  any  mental 
calculations,  for  if  the  color,  of  one  wine  is  represented  by  a  number 
three  times  as  large  as  that  representing  the  color  of  another  we  know 
that  the  first  has  three  times  as  much  color  as  the  latter. 

Professor  Hilgard's  notation  has  been  used  in  the  account  of  experi- 
ment work  detailed  later. 

In  the  absence  of  any  recognized  standard  of  intensity  for  the  color 
of  wines  it  is  difficult  to  say  what  the  proper  degree  of  color  is.  In 
order  to  give  some  idea  of  what  the  numbers  of  Professor  Hilgard's 
scale  indicate  in  practice,  it  may  be  said  that  a  wine  measuring  15  in 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE. 


11 


intensity  would  be  considered  sufficiently  dark  for  an  ordinary  table 
wine.  Any  wine  which  falls  below  10  is  too  light  in  color,  while  any- 
thing over  20  may  be  considered  darker  than  is  necessary.  These 
figures  have  reference  to  the  United  States.  In  Europe  the  popular 
taste  does  not  require  quite  so  much  color. 

A  young  wine  should  contain  more  color  than  these  figures  indicate, 
as  a  certain  proportion  of  the  color  always  drops  during  aging.  This 
loss  of  color  is  most  rapid  during  the  first  two  months  after  fermenta- 
tion. It  becomes  less  rapid  later,  until  after  four  months  the  loss  is 
very  slow.  The  amount  of  loss  varies  very  much  with  different  wines, 
and  with  different  methods  of  handling,  but  a  Zinfandel  to  have  15  of 
color  when  it  is  two  years  old  should  have  at  least  35  or  40  directly 
after  drawing  off  from  the  fermenting  vat,  and,  to  preserve  its  color 
even  so  well  as  this,  it  must  have  full  acidity  and  must  not  be  aged  too 
quickly  by  frequent  racking  or  keeping  in  small  casks  or  warm  cellars. 

The  following  table  is  appended  to  show  the  actual  loss  of  color  found 
by  observation.  The  tests  were  made  with  experiment  wines  fermented 
at  the  Station  cellar,  and  were  all  made  in  small  quantities  and  kept 
in  casks  of  from  10  to  20  gallons.  In  larger  quantities  the  loss  of  color 
would  be  slower,  and  the  depth,  of  color  indicated  for  four  months 
probably  corresponds  to  what  would  be  found  in  practice  in  a  wine  of 
the  same  character  at  the  end  of  eighteen  months  or  two  years: 


TABLE  I. 

Loss  of  Color  during  Aging  of  Wine. 


Number  of  Wines 

Color. 

Examined. 

At  Pressing 

1  Month. 

2  Months. 

3  Months. 

4  Months. 

Four ___  _.  .    

330 
140 
85 
35 
23 
13 

Loss. 
191     42.1% 
95    32.2% 
50    41.2% 
25    28.6% 
15    34.8% 
9    30.7% 

Loss. 

117    64.5% 
91     35.0% 
36    57.6% 
16     54.3% 
11     52.2% 
9    30.7% 

114 

68 
34 
15 
10 

7 

Loss. 

65.4% 
51.4% 
60.0% 

57.1% 
56.5% 
46.2% 

101 
59 

27 

13 

9 

5 

Loss. 

69.4% 
56.8% 
68.2% 
62.9% 
60.9% 
61.5% 

Six 

Five 

Seven    .. _  _'_ 

Five 

Three 

Average  of  color  remaining 

100 

65.1% 

50.9% 

14.2% 

43.9% 

36.5% 

Average   loss   of   original 
color  for  each  month    . 

34.9% 

7-0% 

7-4% 

It  will  be  seen  by  examining  the  table  that  approximately  the  same 
proportion  of  the  color  is  lost  whatever  the  original  color  in  the  wine, 
so  that  it  is  possible  to  foretell  within  very  close  limits  what  the  color  of 
a  wine  will  be  at  the  end  of  a  certain  time  when  kept  under  certain 
conditions.  This  applies  only  to  wines  of  which  the  coloring  matter  is 
normal.  Wines  made  from  such  grapes  as  Lenoir,  Grenache,  Trous- 
seau, or  from  partially  dried  or  moldy  grapes,  lose  their  color  more 
quickly. 


12 


UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 


It  may  be  said,  then,  that  wines  kept  in  very  small  casks  lose  about 
one-third  of  their  color  during  the  first  month,  about  one-half  during 
the  first  two  months,  and  nearly  two-thirds  of  their  color  during  the 
first  four  months  after  pressing. 

The  loss  at  first  is  much  more  rapid  in  the  very  deeply  colored  wines 
than  in  those  more  lightly  colored,  as  is  shown  by  the  curves  in  Fig.  6. 


FIG.  6.     Loss  of  Color  in  Red  Wines  during  the  First  Four  Months. 

The  numbers  on  the  right  show  the  color  at  pressing;  those  on  the  left 
at  four  months.  The  dotted  curve  shows  the  average  loss  calculated  from 
observations  on  thirty  wines. 

Cooling. — As  soon  as  the  extraction  of  the  skins  has  proceeded  far 
enough,  as  indicated  by  the  reading  of  the  colorimeter,  the  must,  now 
containing  tannin  and  color,  is  drawn  off  and  cooled  to  80°  or  85°  F. 
This  was  done  in  the  experiments  by  means  of  the  cooling  machine 
described  in  Bulletin  No.  174.  As  the  must  is  hot  (125°  F.)  and  the 
temperature  has  to  be  lowered  only  to  80°  or  85°  F.,  the  cooling  takes 
place  very  easily  and  rapidly  with  the  cooler  used.  The  hot  must  runs 
off  very  freely,  as  the  pulp  cells  of  the  grapes  have  all  been  thoroughly 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE.  13 

heated  and  have  lost  the  power  of  retaining  the  juice  possessed^by  the 
cells  of  fresh  grapes.  A  certain  amount  of  juice  remains,  however,  in 
the  skin,  most  of  which  can  be  recovered  by  pressing,  as  is  ordinarily 
done  with  fermented  grapes.  It  would  be  better  to  extract  this  juice 
by  some  diffusion  process,  but  so  far  no  satisfactory  method  of  doing 
this  has  been  devised.  In  the  experiments,  only  the  must  which  ran 
off  without  pressing  was  used,  but  it  would  be  very  desirable  to  obtain 
that  remaining  in  the  skins,  as  it  contains  more  color  than  that  in  the 
free  run.  A  continuous  press  would  be  excellent  for  this  purpose,  as 
the  maceration  of  the  pomace  which  occurs  with  such  presses  would  not 
have  the  bad  effect  it  has  when  pressing  fermented  pomace,  because  the 
extra  amount  of  solid  matter  would  be  to  a  great  extent  precipitated 
during  fermentation. 

As  soon  as  the  must  is  cooled  and  run  into  fermenting  vats,  any 
correction  which  it  needs,  such  as  the  addition  of  acid  or  water,  should 
be  made.  At  the  same  time  a  starter  of  yeast  should  be  used,  preferably 
of  tested  pure  yeast. 

Pure  Yeast. — In  the  experiments,  a  pure  Champagne  yeast  was  used. 
This  yeast  had  been  thoroughly  tested  and  found  capable  of  fermenting 
out  very  sweet  musts  and  producing  a  good  wine.  The  same  yeast  was 
used  in  all  the  experiments  and  was  found  to  give  good  results  with 
both  white  and  red  wines. 

Method  of  Using  the  Pure  Yeast. — A  method  was  devised  for  keeping 
a  supply  of  pure  yeast  on  hand  for  the  various  fermentations,  which 
was  found  very  simple  and  convenient.  As  the  method  is  of  general 
application  and  could  be  used  for  the  same  purpose  with  the  ordinary 
methods  of  wine-making,  it  is  described  here. 

The  method  adopted  was  as  follows:  Starting  with  a  4-ounce  flask, 
the  pure  yeast  was  increased  by  pouring  it  into  a  large  flask  containing 
one  gallon  of  must  which  had  just  been  cooled  to  90°  F.  after  sterilizing 
by  boiling.  Three  days  later,  this  gallon  of  must  was  fermenting  well  and 
contained  a  large  amount  of  active  yeast.  In  the  meanwhile  25  gallons 
of  must,  obtained  from  clean,  sound  grapes,  had  been  cleared  of  its  sedi- 
ment and  yeast  by  settling  with  sulfurous  acid.  This  was  done  by 
adding  1  ounce  of  potassium  meta-bisulfite  dissolved  in  one  pint  of 
water  to  25  gallons  of  must.  This  had  the  effect  of  preventing  fer- 
mentation until  all  sediment,  including  the  molds  and  yeast,  in  the 
must  had  settled.  In  twenty-four  hours,  must  treated  in  this  way  was 
perfectly  bright  and  was  racked  off  into  a  clean  cask  which  had  been 
thoroughly  sterilized  by  steaming.  Must  treated  in  this  way  is  prac- 
tically free  from  all  fermentative  organisms.  Five  gallons  of  this  clear 
must  were  then  freed  from  the  sulfurous  acid  by  boiling  and  placed  in 
a  shallow  tub  which  had   been  thoroughly  cleaned  and  sterilized  with 


14  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

boiling  water.  As  soon  as  the  must  in  the  tub  had  cooled  to  90°  F.,  the 
gallon  of  yeast  in  the  flask  was  added  and  the  whole  thoroughly  aerated 
by  dipping  up  the  must  with  a  gallon  measure  and  pouring  it  through 
the  air  back  into  the  tub.  As  soon  as  fermentation  was  well  under  way 
(twenty-four  hours),  2-J  gallons  of  the  clear  must  were  added  without 
previous  boiling.  More  than  this  should  not  be  added  for  fear  of  the 
arrest  of  the  fermentation  which  might  occur  if  too  much  of  the  must 
containing  sulfite  were  added  at  once.  The  next  day,  5  gallons  more  of 
the  clear  sulfited-must  were  added.  It  was  safe  to  add  more  this  time 
as  the  yeast  was  becoming  used  to  the  sulfurous  acid.  Twenty-four 
hours  later  the  remaining  12-J  gallons  of  the  sulfited-must  were  added. 

In  this  way,  at  the  end  of  six  days,  25  gallons  of  must  containing 
pure  yeast  wrere  obtained  practically  free  from  molds,  bacteria,  or  wild 
yeast.  In  order  to  have  a  maximum  amount  of  vigorous  yeast  in  the 
must  it  should  be  thoroughly  aerated  several  times  every  day,  and 
fermented  in  a  low,  wide  tub. 

As  soon  as  a  stock  of  pure  yeast  is  obtained  in  this  way  it  can  be 
kept  up  simply  by  replacing  the  yeast  taken  out  with  an  equal  quantity 
of  clear  sulfited-must  prepared  in  the  way  described.  During  the 
vintage  it  is  not  necessary  to  crush  and  press  grapes  specially  for  this 
purpose,  but  the  must  can  be  taken  directly  from  the  vats  or  casks,  care 
being  taken  to  sulfite  the  must  as  soon  as  it  is  separated  from  the  grapes 
before  the  slightest  fermentation  has  commenced. 

A  stock  of  25  gallons  is  sufficient  for  the  fermentation  of  2,000  gal- 
lons per  day.  Twenty  gallons  may  be  taken  from  the  pure  yeast  tub 
every  day  and  replaced  with  sulfited-must,  and  if  the  temperature  is 
kept  above  80°  F.  and  the  must  is  not  too  sweet  (not  over  22%  B.)  and 
sufficient  aeration  is  given,  the  amount  of  yeast  in  the  must  will  not 
diminish. 

Every  care  should  be  given  to  prevent  contamination  of  the  yeast. 
The  yeast  tub  should  be  kept  covered  with  a  clean  cloth  and  should  be 
placed  in  a  room  separate  from  the  fermenting  vats.  All  tubs,  buckets, 
casks,  hose,  etc.,  used  in  the  production  of  the  yeast  should  be  thor- 
oughly sterilized  with  boiling  water  and  not  used  for  other  purposes. 

While  it  is  not  pretended  that  by  these  means,  however  carefully 
carried  out,  we  are  sure  to  obtain  an  absolutely  pure  culture  of  yeast, 
in  the  sense  that  it  does  not  contain  a  single  germ  or  cell  of  anything 
but  the  yeast  we  start  with,  it  was  found  that,  for  practical  purposes,  it 
preserves  the  culture  pure  during  the  whole  vintage.  As  we  add  the 
yeast  to  grapes  containing  spores  and  germs  of  many  kinds  or  to  imper- 
fectly sterilized  must,  the  few  contaminating  spores  that  may  get 
into  our  pure  yeast  are  quite  harmless.  This  is  true,  however,  only  if 
we  exercise  well  the  precautions  indicated.  If  we  allow  vinegar  flies  to 
get  at  our  yeast  vats,  or  draw  off  the  yeast  with  hoses  used  for  racking 
wine  or  must,  the  yeast  will  quickly  become  badly  contaminated. 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE.  15 

Fermentation, — After  the  red  must  has  been  cooled  and  the  yeast 
added,  fermentation  will  start  immediately.  Within  twenty-four  hours 
the  temperature  will  rise  to  90°  or  95°  F.,  depending  on  the  outside 
temperature  and  the  size  of  the  vat.  Before  it  reaches  95°  F.  the  fer- 
menting must  is  passed  through  the  cooler  and  reduced  to  80°  F.  If 
the  weather  is  not  very  hot,  the  vats  do  not  contain  more  than  from 
1,000  to  3,000  gallons,  and  the  original  density  of  the  must  does  not 
exceed  22%  to  23%  Balling,  this  cooling  will  be  sufficient.  Usually, 
however,  if  we  are  to  have  a  cool  fermentation,  another  cooling  later 
will  be  necessary.  In  the  experiments  two  coolings  were  always  given, 
and  wines  containing  over  14%  of  alcohol  and  in  one  case  over  15% 
fermented  out  perfectly  dry. 

After  Fermentation. — With  musts  containing  no  more  than  22%  Bal- 
ling, it  is  possible  to  obtain  perfectly  dry  wines  in  four  to  five  days  in 
the  fermenting  vats.  To  insure  this,  a  certain  amount  of  aeration 
should  be  given  at  each  cooling.  This  is  accomplished  simply  by  allow- 
ing the  stream  of  cooled  must  to  fall  through  the  air  a  distance  of  three 
or  four  feet  into  the  vat.  The  must  will  in  this  way  carry  down  enough 
air  to  keep  the  yeast  working  vigorously.  This  aeration  will  at  the 
same  time  get  rid  of  any  excess  of  sulfurous  acid  which  may  be  present. 
In  the  experiment  wines,  this  was  accomplished  so  perfectly  that  only 
the  faintest  traces  of  the  acid  were  found  in  the  finished  wines,  an 
amount  less  than  one-fiftieth  of  that  allowed  in  French  wines  imported 
into  the  United  States. 

More  aeration  than  is  necessary  for  the  completion  of  the  fermenta- 
tion should  be  avoided,  on  account  of  its  effect  on  the  color,  which  is 
diminished  in  quantity  and  injured  in  quality  by  excessive  exposure  to 
the  oxygen  of  the  air. 

With  musts  containing  over  24%  Balling  it  will  usually  be  found 
impossible  to  ferment  the  wine  perfectly  dry  in  the  four  days,  but  it  is 
inadvisable  to  leave  it  in  the  open  fermenting  vats  any  longer  than  this. 
At  the  end  of  four  days,  whatever  the  strength  of  the  original  must,  the 
fermentation  will  be  very  slow.  If  the  temperature,  however,  has  never 
exceeded  95°  F.  it  will  not  have  ceased  entirely,  and  every  effort  should 
be  made  to  keep  it  going  until  the  wine  is  perfectly  dry.  It  is  a  capital 
mistake  to  allow  the  fermentation  to  stop  and  the  yeast  to  settle 
while  the  wine  still  contains  .5%,  1%,  or  even  2%  of  sugar,  as  is  often 
done  in  the  hope  that  the  fermentation  will  recommence  in  the  spring 
and  eliminate  this  sugar. 

At  the  end  of  four  days  in  the  open  vat  the  wine  should  be  trans- 
ferred to  a  storage  cask  however  much  sugar  it  still  contains.  This 
transfer  should  be  made  with  thorough  aeration,  and  the  receiving  cask 
should  not  be  sulfured.     The  wine  should  run  in  a  stream  which  falls 


16  UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 

through  the  air  into  the  pump-tub,  or  well,  and  should  enter  the  storage 
cask  through  the  upper  bunghole  so  that  it  will  fall  through  the  air  in 
the  cask,  unless  some  other  means  is  adopted  for  supplying  the  needed 
oxygen. 

This  aeration  will  reinvigorate  the  yeast  and  will  usually  be  sufficient 
to  keep  the  fermentation  going  until  the  wine  is  dry.  The  wine  should 
be  watched,  however,  and,  if  in  seven  days  it  is  not  dry,  it  should  be 
aerated  again  by  running  it  off  from  the  bottom  of  the  cask  and  pumping 
it  back  into  the  same  cask.  In  the  experiments  this  was  found  sufficient, 
even  in  cases  where  the  resulting  wine  showed  over  15%  of  alcohol,  to 
bring  the  wine  to  dryness  in  three  weeks  from  the  time  the  grapes  were 
crushed. 

By  this  means  the  dangerous  bacterial  fermentations,  which  so  often 
injure  wines,  even  when  they  do  not  spoil  them,  during  the  one  or  two 
months  following  the  vintage,  will  be  avoided.  The  presence  of  a  small 
quantity  of  sugar  in  the  wine  can  not  be  detected  by  means  of  the 
ordinary  saccharometer  or  mustimeter  used  by  cellermen.  The  saccha- 
rometer  may  descend  to  the  0  mark,  or  even  considerably  below  in  wines 
which  contain  over  1%  of  sugar.  This  is  especially  true  of  highly  alco- 
holic wines,  which  are  the  most  troublesome  to  get  dry.  The  taste  of 
the  wine-maker  is  the  only  practical  means  of  determining  the  presence 
of  a  dangerous  residue  of  sugar  in  the  wine. 

So  long  as  a  taste  of  sweetness  can  be  perceived  in  the  wine  by  a 
practiced  taster,  means  should  be  adopted  to  keep  the  fermentation 
going.  For  this  purpose,  usually  all  that  is  necessary  is  an  occasional 
aeration  and  stirring  up  of  the  yeast,  as  already  described.  Prompt 
action,  however,  is  necessary.  The  wine  should  never  be  allowed  to  get 
cold  before  it  is  quite  dry.  If  the  wine  is  placed  in  puncheons  or  other 
small  casks  it  is  very  useful,  if  not  quite  necessary,  to  keep  it  in  a  room 
where  the  temperature  does  not  fall  below  70°  F.  If  it  is  placed  in 
large  casks  (1,000  to  5,000  gallons  or  larger),  it  will  retain  its  heat  for 
a  sufficient  time  to  become  perfectly  dry  if  the  needed  aeration  is  given. 

If,  even  with  these  measures  properly  carried  out,  the  wine  still 
remains  sweet,  it  means,  provided  the  grapes  used  were  not  excessively 
moldy,  that  the  original  must  contained  more  sugar  than  it  is  possible 
for  the  yeast  to  eliminate.  If  the  must  contains  more  than  28%  Ball- 
ing, as  will  sometimes  happen,  especially  when  partially  dried  grapes 
are  present,  there  is  usually  no  possibility  of  fermenting  it  dry.  In  this 
case,  the  sugar  may  be  eliminated  by  blending  with  a  wine  contain- 
ing less  than  12%  of  alcohol.  This  blending,  however,  must  be  done 
promptly,  before  either  wTine  has  become  cold  and  before  the  wine  con- 
taining sugar  has  become  injured  by  bacterial  fermentation.  If  a  wine 
is  not  perfectly  dry  within  seven  days  after  being  transferred  from  the 
fermenting  vat  to  the  storage  cask,  an  alcohol  determination  should  be 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE.  17 

made.  If  there  is  more  than  a  mere  trace  of  sugar  and  the  alcohol 
exceeds  14-J%,  the  wine  should  be  blended  immediately  with  a  weaker 
wine  and  aerated  again. 

First  Racking. — While,  so  long  as  any  sugar  remains,  our  efforts 
should  be  directed  toward  keeping  the  yeast  vigorous  and  suspended  in 
the  wine,  we  should  use  means  to  accomplish  the  opposite  results  as 
soon  as  the  sugar  has  all  disappeared  and  the  wine  is  perfectly  dry. 

The  function  of  the  yeast  is  to  change  the  sugar  of  the  must  into  the 
alcohol  of  the  wine.  As  soon  as  this  is  effected  the  wine  should  be 
freed  from  the  yeast  as  soon  as  possible.  If  the  fermentation  has  been 
conducted  successfully,  the  yeast  will  commence  to  deposit  immediately 
and  the  wine  will  be  comparatively  clear  within  two  or  three  weeks 
after  it  has  become  dry.  The  first  racking,  then,  should  take  place  at 
this  time  and,  as  there  is  no  need  for  further  fermentation,  the  casks 
into  which  the  wine  is  racked  should  be  sulfured.  This  should  be  done 
with  both  red  and  white  wines.  The  sulfur  will  remove  a  little  of  the 
color  in  the  former  case,  but  some  of  this  will  return  as  the  sulfurous 
acid  disappears,  and  the  color  remaining  will  be  much  more  stable. 
Properly  sulfured  red  wines  will  show  more  color  at  the  end  of  six 
months  than  similar  wines  which  have  not  been  sulfured. 

It  is  neither  necessary  nor  advisable  to  wait  until  the  wine  is  perfectly 
clear  before  making  the  first  racking.  All  wines  made  by  commercial 
methods  contain  a  few  bacteria  and  many  of  them  a  great  many,  and 
even  when  wines  taste  dry  there  is  often  a  trace  of  sugar  left  which  is 
sufficient  to  serve  as  nourishment  for  the  bacteria.  It  is  verv  desirable, 
therefore,  to  put  the  wine  in  such  a  condition  that  the  bacteria  will  be 
deposited  and  the  wine  cleared  as  soon  as  possible.  This  is  accomplished 
by  racking  without  aeration,  which  eliminates  the  yeast  and  bacteria 
in  the  thick  lees,  and  by  sulfuring  and  cooling,  which  stop  the  action 
of  the  floating  bacteria  and  cause  them  to  be  deposited. 

After  the  first  racking,  or  before,  if  the  wine  is  perfectly  dry  to  the 
taste,  the  cellar  should  be  kept  as  cool  as  possible  and  the  wine  pro- 
tected as  much  as  possible  from  the  air,  in  order  to  promote  the  settling 
of  all  the  fine  lees  and  hasten  the  perfect  clearing  of  the  wine. 

experiments:  red  wine. 

I.  Over-ripe  Grapes;  Extraction  by  Heat;  Use  of  Cooler;  Pure 
Yeast. — On  August  21st,  at  3  p.  m.,  about  twelve  tons  of  Zinfandel  grapes 
were  passed  through  the  crusher  and  stemmer  and  pumped  by  means 
of  a  must  pump  into  a  vat  furnished  with  a  strainer.  The  grapes  were 
very  ripe,  writh  a  large  proportion  of  shriveled  berries,  and  some  quite 
dry.  There  were  abundant  signs  of  Mildew  (Oidium)  and  some  Black 
Mold  (Aspergillus).  The  must  showed  26%  Balling  and  .55%  of  acid 
bul.  177—2 


18  UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 

immediately  after  crushing  and  before  the  sugar  from  the  dried  grapes 
had  diffused  out  into  the  must.  There  was  a  very  little  second  crop 
present. 

Before  placing  the  grapes  in  the  vats,  the  latter  were  thoroughly 
washed  and  then  swabbed  with  a  3%  solution  of  sulfuric  acid,  which 
was  left  on  the  wood  for  several  hours  and  then  rinsed  off  with  water. 
This  treatment  was  given  to  all  the  vats  used  in  the  experiments. 

As  soon  as  the  vat  was  full,  the  must  was  drawn  off  and  passed 
through  the  Gomot  heater,  from  which  it  passed  with  a  temperature  of 
140°  F.  back  on  to  the  skins  in  the  original  vat.  This  was  continued 
with  occasional  stirring  of  the  grapes  until  the  contents  of  the  vat  had 
reached  a  temperature  of  112°  F.  Before  passing  the  must  through  the 
heater,  3.75  pounds  of  potassium  meta-bisulfite  were  added  to  it  to 
prevent  the  oxidizing  effect  of  the  air  on  the  heated  grapes. 

At  7  a.  m.  of  the  next  day,  August  22d,  the  must  in  the  vat  was  red, 
but  not  deeply  colored.  The  color  was  2VR,  49.4.  (See  page  10.)  The 
must  at  this  time  showed  27%  Balling,  owing  to  the  diffusion  of  the 
sugar  from  the  dried  grapes  into  the  must.  The  acid  was  .65%  and  the 
tannin  .32%.  The  tannin  was  sufficiently  high,  but  in  order  to  increase 
the  color  it  was  decided  to  heat  the  vat  again. 

At  9  a.  m.  the  must  was  drawn  off  again  and  passed  through  the 
heater  at  150°  to  158°  F.  and  back  on  to  the  skins  until  the  whole  vat 
showed  133°  F. 

At  10  a.  m.  the  color  had  increased  to  2VR,  65.6,  and  the  tannin  to 
.352%. 

At  4  p.  m.  of  the  same  day  the  red  must  was  run  through  the  cooler, 
reduced  in  temperature  to  84°  F.,  and  a  starter  of  15  gallons  of  Cham- 
pagne yeast  (see  p.  13)  added.  Later,  250  gallons  of  water  and  5 
pounds  of  citric  acid  were  added  to  the  1,700  gallons  of  must. 

The  progress  of  the  fermentation  is  shown  below: 

Sugar.  Temperature. 

Aug.  22,    6:00p.  m 27%  B.  84°  F. 

Aug.  23,    6:00  a.  m.,  fermenting  well 25  85 

12:00  m.,  water  and  acid  added. 

1:00p.  m 22  84 

Color,  3VR,  58;  Acid,  .66%;  Tannin,  .35%. 

5:00  p.  m.,  passed  through  cooler 19  90 

7:00p.m.. 19  84 

Aug.  24,     7:00  a.  m.,  cooled  to  84°  F 16  92 

Color,  1VR,  41.2. 

12:00  m. 13i  87 

5:00p.  m 12  89 

Aug.  25,     7:00  a.  m.,  cooled  to  90° 7  96 

Color,  3VR,  27.5. 

12:00m 5.2  90 

6:00p.  m 4.5  89 

Aug.  26,     6:00  a.  M - 2.5  93 

12:00m.... 1.5  93 

Racked  into  storage  vat. 
Aug.  27,  Nearly  dry. 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE. 


19 


On  September  1st  the  wine  showed  13.5%  of  alcohol  and  the  color 
was  4VR,  26.3.  On  September  7th  it  was  nearly  clear,  and  was  racked 
into  puncheons,  and  in  a  few  days  was  quite  dry  and  clear. 

This  experiment  shows  that  heating  the  grapes  to  112°  F.  is  not  suffi- 
cient to  extract  the  maximum  amount  of  color  of  ripe  Zinfandel,  even 
though  the  grapes  are  kept  hot  for  fifteen  hours. 

The  fermenting  wine  was  cooled  three  times.  This  was  necessary 
because  the  regular  cooling  machine  was  not  ready  for  use  and  a  tem- 
porary and  less  efficient  device  had  to  be  used.  The  fermenting  wine 
was  lowered  20°  F.  by  the  three  coolings.  This  could  have  been  done, 
as  was  proved  later,  by  one  cooling  of  two  hours  at  the  rate  of  750 
gallons  per  hour  with  the  form  of  cooling  machine  finally  adopted,  or 
by  two  coolings  of  one  hour  at  the  same  rate.     The  effect  on  the  fer- 


FIG.  7.    Color,  Sugar,  and  Temperature  Changes  of  Experiment  I. 

mentation,  however,  was  the  same,  and  it  continued  without  interruption 
until  the  wine  was  dry  at  six  days,  with  13.5%  of  alcohol.  It  is  instruct- 
ive to  compare  this  result  with  Experiment  III,  where  the  cooling  was 
intentionally  less  complete.  The  wine  of  Experiment  III  required 
thirty  days  to  become  dry,  though  the  alcohol  in  the  wine  was  1%  less 
than  in  the  wine  of  this  experiment. 

An  examination  of  Fig.  7  shows  that  the  curve  representing  the 
diminution  of  color  during  fermentation  is  for  the  first  three  days  very 
nearly  parallel  to  that  representing  the  diminution  of  the  sugar-content. 
This  probably  indicates  that  the  part  of  the  color  insoluble  in  alcohol 
is  deposited  in  the  same  ratio  as  the  alcohol  is  produced  by  the  fermen- 
tation of  the  sugar.  This  rapid  fall  of  the  color  ceases  on  the  fourth 
day,  the  color  which  remains  at  this  time  being  soluble  in  alcohol,  and 
the  further  production  of  alcohol  has  little  or  no  effect  on  it.  The 
number  27  representing  the  color  at  the  end  of  the  fourth  day  probably 


20  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

indicates  the  whole  amount  of  the  original  color  in  the  grapes  which  is 
capable  of  remaining  dissolved  in  the  fermented  wine.  Whether  all  of 
this  could  have  been  extracted  by  the  ordinary  methods  of  fermentation 
is  not  shown  by  the  experiment,  but  a  comparison  with  the  results  of 
Experiment  III  indicates  that  it  could  not.  The  wine  of  the  latter 
experiment,  made  from  grapes  similar  to  those  used  in  Experiment  I, 
had  only  18  of  color  at  the  end  of  the  fermentation.  With  regard  to 
the  stability  of  the  color  the  comparison  is  even  more  strikingly  in  favor 
of  the  new  method.  At  the  end  of  three  months  the  color  of  the  wine 
of  Experiment  I  was  practically  the  same  as  when  the  fermentation 
had  finished  at  four  days,  while  the  wine  of  Experiment  III  had  lost 
28%  of  its  color. 

The  broken  line  in  Fig.  7  shows  the  temperature  changes  observed 
during  the  fermentation.  A  drop  in  temperature  occurred  four  times. 
The  first,  a  slight  drop,  was  due  to  the  addition  of  cold  water  used  to 
dilute  the  must.  The  other  three  drops  are  the  effects  of  the  coolings 
which  were  given  when  the  fermenting  wine  reached  90°,  92°,  and 
96°,  respectively.  A  point  of  interest  in  this  curve  is  that  the  abrupt 
changes  in  temperature  had  practically  no  effect  on  the  rapidity  of  fer- 
mentation, as  is  shown  by  the  even  curve  representing  the  disappear- 
ance of  sugar.  A  slight  irregularity  of  the  sugar  curve  may  be  noticed 
opposite  each  jog  representing  a  cooling  on  the  temperature  curve,  but 
the  irregularity  is  so  slight  that  it  is  of  no  practical  importance.  This 
is  shown  equally  in  Experiment  IX  (see  Fig.  10,  page  25),  where  cool- 
ings of  13°  F.  and  14°  F.  show  hardly  any  appreciable  effect  on  the  rate 
of  fermentation.  This  lack  of  apparent  influence  of  the  cooling  on  the 
rate  of  fermentation  is  probably  due  to  the  fact  that  each  cooling  was 
accompanied  by  an  aeration  which  invigorated  the  yeast  and  counter- 
acted the  retarding  effect  of  the  lower  temperature. 

II.  Under-ripe  Grapes;  Use  of  Cooler ;  Pure  Yeast. — On  August  25th 
about  twelve  tons  of  Zinfandel  grapes  were  crushed,  stemmed,  and 
pumped  into  a  fermenting  vat,  a  starter  of  pure  Champagne  yeast  being 
added  as  the  grapes  came  into  the  vat.  The  grapes  were  poorly  colored 
and  not  thoroughly  mature.  They  showed  22.7%  Balling  and  .66%  of 
acid.     The  record  of  the  fermentation  is  as  follows: 

Sugar.      Temperature. 

Aug.  25,  10:00  a.  m . 22.7%  B.  71°  F. 

7:00p.  m 22.2  74 

Aug.  26,    7:00  a.  m.,  fermenting  well 22.4  78 

12:00m.,   fermenting  well 20.4  78 

7:00  p.  m.,  fermenting  well 19.2  88 

Aug.  27,    7:00  a.  m.,  cooled  to  90°  F 6.0  96 

12:00  m 5.5  90 

7:00p.  M 4.0  92 

Aug.  28,    7:00  v.  m.,  racked  into  storage  vat 1.0  94 

Aug.  29,  Dry. 

Sept.    7,  The  wine  was  still  cloudy,  but  was  racked  into  puncheons. 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE. 


21 


This  experiment  illustrates  the  fact  that  even  when  the  grapes  are 
gathered  incompletely  mature,  the  temperature  of  the  fermentation 
must  be  controlled  in  a  hot  climate  if  we  are  to  produce  a  dry  wine; 
and  it  also  shows  that  we  can  not  expect  to  produce  wine  of  good 
quality  from  unripe  grapes,  as  will  be  seen  by  comparing  the  quality  of 
the  various  experiment  wines  as  given  on  page  27. 

The  checking  of  the  fermentation  at  the  time  of  cooling  is  more  per- 
ceptible in  this  fermentation  than  in  any  of  the  others.  In  this  case, 
as  in  that  of  the  last  cooling  in  Experiment  IX,  the  checking  at  cooling 
is  probably  merely  a  coincidence  and  due  in  reality  to  the  large  amount 
of  alcohol  present  at  that  stage  of  the  fermentation.  The  upward 
course  of  the  temperature  curve  (Fig.  8)  during  the  first  day  without 


I  SC.  VtlU 


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FIG    8.    Sugar  and  Temperature  Changes  of  Experiment  II. 

any  corresponding  decrease  of  sugar  is  due  undoubtedly  simply  to 
errors  of  observation.  It  is  extremely  difficult  to  take  an  average 
sample  for  either  sugar  or  temperature  determination  in  a  vat  of  crushed 
grapes  immediately  after  filling.  Later,  after  fermentation  has  com- 
menced and  the  grapes  have  been  well  stirred,  the  observations  are  much 
less  liable  to  error.  The  average  temperature  of  this  vat  at  the  begin- 
ning was  undoubtedly  higher  than  71°  F.  The  same  peculiarity  is  seen 
in  the  curves  of  Fig.  9. 


III.  Ripe  Grapes;  Incomplete  Cooling;  Sulfite;  Pure  Yeast. — On 
August  25th  about  twelve  tons  of  Zinfandel  grapes  in  fair  condition, 
except  for  a  considerable  amount  of  black  mold,  were  crushed,  stemmed, 
and  pumped  into  a  fermenting  vat.     The  must  showed  23.7%  Balling 


22 


UNIVERSITY  OF  CAEIFORNI A—  EXPERIMENT  STATION. 


and  .66%  of    acid.     Pure  Champagne  yeast  was  added  as  the  grapes 
came  into  the  vat.     The  record  of  fermentation  is  as  follows: 


Aug 


Sugar. 

Aug.  25,    6:00p.  m 23.7%B. 

Aug.  26,     7:00  A.  M 23.2 

12:00  m.,  fermenting  well 20.0 

6:00  p.  m 16.0 

27,     6:00  a.m.-.. 7.2 

12:00  m.,  cooled  to  90°  F.  and  added  two  pounds 

sulfite -     6.0 

6:00p.  m 6.0 

Aug.  28,    6:00  a.  m.,  evidently  "stuck" 6.0 

12:00  m. 5.5 

6:00p.  M 5.0 

Aug.  29,     6:00  A.  m 5.0 

12:00m. 5.0 

6:00p.  m 4.5 

Aug.  30,    4.0 

Aug.  31,  Racked  into  storage  vat 3.0 


Temperature. 
74°  F. 
82 
85 
90 
96 

98 
90 
88 
89 
90 
92 
92 
90 
92 
90 


3#° 

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3rd    J)dlj 

If.th.Day 

FKI.  9.    Sugar  and  Temperature  Changes  of  Experiment  III. 

On  September  1st  the  color  was  5VR,  18.7,  and  the  wine  remained 
sweet  until  September  11th,  when  it  was  pumped  over  for  an  hour.  On 
September  22d  it  was  nearly  dry,  but  still  cloudy. 

This  experiment  shows  the  danger  of  allowing  the  fermentation  to 
rise  as  high  as  98°  F.,  but  also  the  possibility  of  getting  it  through  com- 
pletely within  a  few  weeks  without  any  serious  damage  to  the  quality. 
In  this  case  the  chief  loss  was  the  extra  trouble  and  time  needed  to  get 
the  wine  dry.  The  cooling  ought  to  have  been  done  very  early  on  the 
morning  of  August  27th  instead  of  waiting  until  the  afternoon.  It  was 
a  mistake  also  to  add  the  sulfite  at  noon  on  August  27th.  The  sulfite, 
if  used  at  all,  should  have  been  added  on  the  evening  of  August  26th, 
before  the  high  temperature  was  reached. 

The  curves  of  Fig.  9  are  instructive  in  several  particulars.  Compared 
with  those  of  Fig.  10  they  show  plainly  that  the  hottest  fermentation 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE.  23 

is  not  necessarily  that  which  finishes  first.  In  Fig.  9  the  sugar  curve 
drops  very  rapidly  from  the  middle  of  the  first  day  to  the  middle  of 
the  second,  when  it  comes  to  an  abrupt  stop,  becoming  almost  hori- 
zontal for  twenty-four  hours.  The  rapid  loss  of  sugar  is  accompanied 
by  a  corresponding  rapid  rise  in  temperature  due  to  the  former.  The 
temperature  of  98°  reached  practically  stops  the  fermentation  com- 
pletely for  twenty-four  hours.  This  is  shown  both  by  the  sugar  remain- 
ing unchanged  and  by  the  temperature  falling.  The  wine  was  cooled 
from  98°  to  90°  by  the  machine,  and  then  instead  of  rising  again,  as  it 
would  have  done  if  there  had  been  any  active  fermentation  going  on 
and  as  it  did  after  every  cooling  in  Experiments  I  and  IX  (see  Figs.  5,  7, 
and  10),  it  fell  to  88°.  This  shows  that  there  was  not  enough  fermenta- 
tion going  on  to  counterbalance  the  heat  lost  by  radiation.  The  vat 
had  "stuck."  The  "sticking,"  however,  was  not  so  serious  as  it  often 
is  in  vats  which  rise  higher  than  98°,  or  stay  at  this  temperature  for 
some  time.  The  cooling  as  soon  as  the  temperature  reached  98n,  and 
the  aeration  practiced  afterwards,  revived  the  fermentation,  as  is  shown 
by  the  gradual  rise  of  the  temperature  curve  and  the  fall  of  the  sugar 
curve. 

IV.  Over-ripe  Grapes;  Dilution;  Addition  of  Acid. — On  September  1st 
at  11  a.  m.,  five  tons  of  Zinfandel  grapes  were  crushed  and  stemmed 
into  a  fermenting  vat.  The  grapes  were  over-ripe,  some  of  the  berries 
dried,  and  there  was  a  large  amount  of  black  mold.  The  must  showed 
29.5%  Balling  and  .7%  acidity.  It  was  diluted  with  250  gallons  of  water, 
to  which  was  added  6  pounds  of  tartaric  acid. 

The  temperature  of  the  grapes  at  the  start  was  73°  F.,  and  within 
thirty-six  hours  had  risen  to  90°  F.  at  the  bottom  of  the  vat  and  104°  F. 
in  the  cap.  The  fermentation  stuck  when  the  sugar  had  fallen  to  7% 
Balling,  and  could  not  be  revived  by  cooling.  The  wine  was  used  for 
port,  as  an  attempt  to  make  it  dry  would  probably  have  resulted  in 
spoiling  it  completely. 

This  experiment  shows  the  futility  of  attempting  to  make  a  dry  wine 
in  a  hot  climate  from  over-ripe  grapes,  even  if  the  acidity  is  increased 
artificially  and  the  sugar  decreased  by  dilution,  unless  we  adopt  some 
means  of  controlling  the  temperature. 

V.  Over-ripe  Grapes;  Dilution;  Addition  of  Acid;  Control  of  Tem- 
perature by  Use  of  Sulfites. — A  vat  of  Zinfandel  grapes,  similar  in  every 
respect  to  those  used  in  Experiment  IV,  was  diluted  and  acidified  in 
exactly  the  same  way  and  an  attempt  made  to  control  the  temperature 
by  the  occasional  addition  of  a  calculated  amount  of  a  solution  of 
potassium  meta-bisulfite.  The  experiment  was  a  failure,  as  the  temper- 
ature ran  up  to  a  higher  point  than  that  reached  in  Experiment  IV,  and 
the  wine  stuck  with  12%  Balling. 


24 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 


This  was  by  no  means  a  conclusive  test  of  the  method,  as  the  amount 
of  sulfite  used  was  too  small.  The  use  of  sulfite  was  tested  again  in 
Experiment  VII. 

VII.  Ripe  Grapes;  PureYeast;  Control  of  Temperature  }>y  Use  of 
Sulfites;  Pomace  and  Must  Fermented  Separately. — (Debono  method, 
see  Bulletin  No.  167,  p.  18.)  The  grapes  used  in  this  experiment  con- 
sisted of  29%  Charbono,  29%  Lenoir,  and  42%  Burger;  nine  tons  in  all. 
They  were  ripe  and  in  good  condition,  the  mixture  showing  22.5%  Ball- 
ing.    The  following  is  the  record  of  the  fermentation: 

September  2d,  3:00  p.  m.  Crushed  and  added  potassium  meta-bi- 
sulfite  solution  (=.06  per  mil.)  and  15  gallons  of  Champagne  yeast 
accustomed  to  sulfite. 

September  3d,  7:00  a.  m.  The  fermentation  had  commenced,  and  the 
must  was  drawn  off  into  an  open  vat  and  given  another  dose  of  sulfite 
solution  twice  as  large  as  the  first  dose  (=.12  per  mil.).  The  must 
and  pomace  were  then  allowed  to  ferment  separately. 

The  further  progress  of  the  fermentation  is  shown  by  the  following 
table: 


Must. 


Temp. 


Sept,    3,  6:00  p.  m 

Sept,    4,7:00  a.  m. 

5:00p.  m .    ._. 

Added  more  sulfite  (=.12  per  mil.). 
Sept,    5,    7:00  a.m.    

12:00  m 


74°  F. 

86 

94 

96 
98 


Sugar. 


22.5%  B, 

13 

10 

4.5 
2.5 


Pomace. 


Temp. 


74°  F. 

94 

98 

100 

100 


Sugar. 


22.5%  B. 
6 
2.5 

1.5 
1.0 


:00  p.  m. 


Sept.    6, 


Sept. 
Sept. 
Sept. 


The  must,  which  had  fallen  to  2%  Balling,  was  now  pumped  back  on 
to  the  pomace  and  allowed  to  stand,  after  a  thorough  stirring,  for 
twenty-four  hours.  When  first  mixed,  the  vat  showed  a  temperature 
of  98°'F.  and  2%  Balling. 
7:00  a.  m.     Temperature  92°  F.,  sugar  1.5%  Balling. 
12:00  m.     Racked  off  pomace  into  open  vat  and  aerated.     The  color  of  the  wine 
was  2VR,  20.3. 
7.     The  wine  was  transferred  to  a  storage  cask. 
11.     The  wine  still  tastes  a  little  sweet  and  was  pumped  over  for  one  hour. 
22.     Still  shows  a  slight  trace  of  sweetness. 


While  this  wine  did  not  stick  entirely  and  finally  went  through  per- 
fectly dry,  there  is  no  evidence  in  the  experiment  that  the  addition  of 
the  sulfite  had  the  slightest  effect  in  preventing  high  temperatures.  The 
grapes  had  only  22.5%  of  sugar  and  were  cool  (74°  F.)  when  crushed. 
If  we  reckon  that  each  per  cent  of  sugar  in  fermenting  heats  the  must 
1.17°  F.,*  the  temperature  of  the  fermenting  grapes  should  have  reached 
97.5°  F.  when  20%  of  sugar  had  fermented  out.  This  corresponds 
almost  exactly  to  what  occurred,  so  that  there  is  no  delay  of  fermenta- 
tion or  moderation  of  temperature  that  can  be  accredited  to  the  sulfite. 
If  sulfites  are  to  be  effective  for  this  purpose  they  must  evidently  be 
used  in  larger  doses  than  those  adopted  in  this  experiment. 


*See  Bulletin  No.  174,  pp.  17,  18,  19. 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE. 


25 


IX.  Ripe  Graces;  Pure  Yeast;  Extraction  by  Heat;  Temperature 
Controlled  by  Cooling  Machine. — The  grapes  used  in  this  experiment 
were  a  mixture  of  Grenache  45%,  Zinfandel  31-J%,  and  Lenoir  23-J%. 
They  were  mature  and  in  good  condition  except  for  a  few  dried  and 
moldy  grapes  and  some  green  bunches  of  second  crop  in  the  Zinfandel. 
The  must  was  passed  through  the  heater  and  back  on  to  the  pomace 
until  the  temperature  of  the  whole  was  125°  F.,  and  the  whole  well 
stirred.  This  was  on  the  afternoon  of  September  8th,  and  at  9  a.  m. 
of  September  9th  the  must  was  drawn  off  the  pomace  and  cooled.     The 


FIG    10.     Sugar  and  Temperature  Changes  of  Experiment  IX. 

color  of  the  must  was  1  VR,  53.4.     Yeast  was  added,  and  the  fermenta- 
tion proceeded  as  follows: 


Sept. 


Sugar.       Temperature. 


9,    4:O0p.  m 23.0%B.         84°  F. 

7:00  p.  m.,  cooled  to  80° 21.5  87 

10:00  p.  m 19.0  80 

Sept.  10,    7:00  a.  m  ,  cooled  to  79° 12.5  92 

10:00  a.m. 12.0  79 

10:00p.m. 8.0  85 

Sept.  11,    7:00  a.  m.,  cooled  to  78° 4.5  92 

12:00m 3.0  78 

6:00  p.  m 2.5  78 

Sept.  12,    7:00  a.  m.,  transferred  to  a  storage  cask 1.0  79 

Sept.  19,    Still  a  little  sweet  and  still  fermenting. 
Sept.  23,    Pumped  over  for  one  hour. 

This  experiment  exemplifies  the  benefit  to  be  derived  from  complete 
control  of  the  temperature  by  efficient  cooling.  The  wine  required  a 
month  to  become  quite  dry,  but  at  the  end  of  that  time  all  the  sugar 
was  eliminated,  although  the  wine  contained  15.1%  of  alcohol.  It 
became  dry  as  soon  as  did  the  wine  of  Experiment  III,  which  contained 
only  12.5%  of  alcohol  but  was  allowed  to  reach  a  temperature  of  98°  F. 
The  wine  was  cooled  three  times,  a  total  of  27°  F.  being  taken  out  by 
the  cooler.     The  same  result  could  have  been  obtained  with  considerably 


26  UNIVERSITY  OP  CALIFORNIA  — EXPERIMENT  STATION. 

less  cooling  if  in  order  to  avoid  night  work  the  first  cooling  had  not 
been  done  sooner  than  was  necessary.  The  last  cooling,  moreover, 
was  much  greater  than  was  necessary  and  might  have  been  dispensed 
with  altogether. 

The  sugar  curve  in  Fig.  10  is  in  marked  contrast  with  that  of  Fig.  9. 
The  drop  in  the  curve  is  just  as  rapid  during  the  first  thirty-six  hours, 
but  instead  of  being  checked  there  it  continues  for  forty-eight  hours 
until  the  sugar  reaches  3%.  Here  the  fermentation  is  checked  slightly 
but  not  "  stuck,"  and  the  wine  was  practically  dry  in  three  days  when 
Experiment  III  still  had  5%  of  sugar.  This  difference  is  undoubtedly 
due  altogether  to  the  fact  that  Experiment  IX  was  not  allowed  to  rise 
above  92°  F. 

experiments:  white  wine. 

VI.  Defecation  by  Sulfuring;  Pure  Yeast;  Fermentation  in  Punch- 
eons.— The  grapes  used  in  this  experiment  were  about  eight  tons  of 
Johannisberg  and  Franken  Riesling.  They  were  in  excellent  condition 
and  were  a  striking  example  of  what  can  be  done  by  proper  care  and 
cultivation,  even  with  varieties  presumably  so  unsuited  to  a  hot  climate 
as  the  grapes  of  the  Rhine.  The  grapes  were  thoroughly  and  evenly 
matured  and  showed  no  sunburn,  mildew,  or  mold. 

They  were  crushed  into  an  open  vat,  and  the  first  500  gallons  of  must 
which  ran  off  was  pumped  into  a  heavily  sulfured  cask.  After  settling 
for  twenty-four  hours,  the  must  was  drawn  off  into  three  sulfured 
puncheons  and  started  with  pure  Champagne  yeast. 

The  following  is  the  record  of  the  fermentation: 

Date.  Sugar.      Temperature. 

August  26th 22.5%  B.  78°  F. 

August  27th 16.7  85 

August  28th 9.1  88 

August  29th 4.7  88 

August  30th 2.8  88 

August  31st 2.0  87 

The  wine  fermented  slowly,  and  on  September  2d  was  still  a  little 
sweet.  It  was  then  pumped-over  to  aerate  it,  and  on  September  8th 
was  dry  and  nearly  clear. 

Via.  Fermentation  Started  on  Skins;  Pure  Yeast;  Fermentation  in 
Puncheons. — After  drawing  500  gallons  of  must  off  the  crushed  grapes 
of  Experiment  VI,  the  remainder  was  left  on  the  skins  for  twelve  hours. 
At  the  end  of  this  time  a  slight  fermentation  was  perceptible,  and  the 
must  was  drawn  off  into  sulfured  puncheons  and  started  with  Cham- 
pagne yeast.     The  folloAving  is  the  record  of  the  fermentation: 

Date.  Sugar.     Temperature. 

August  26th 25.0%  B.  78°  F. 

August  27th 8.7  92 

August  28th 5.9  89 

August  29th 4.4  87 

August  30th 4.0  86 

August  31st 4.0  84 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE. 


27 


The  wine  was  treated  in  the  same  way  as  in  Experiment  VI,  but  on 
September  8th  it  was  still  cloudy  and  slightly  sweet.  On  September 
22d  it  was  cloudy  and  fermenting  and  had  a  slight  brownish  color.  It 
finally  became  nearly  dry  about  October  21st,  and  the  brownish  tint 
had  almost  disappeared,  though  it  was  still  cloudy. 

A  50-gallon  cask  of  each  experiment  wine  was  shipped  to  Berkeley 
and  stored  in  the  Station  cellar.  They  were  tasted  on  November  24, 
1905,  with  the  following  results: 

Exp.  I.  Perfectly  clear,  full  flavor,  sound,  fruity,  and  agreeable,  but 
with  a  slight  taste  of  dried  grapes. 

Exp.  II.     Cloudy,  of  poor  color  and  a  little  mousey. 

Exp.  III.     Clear  and  a  good  wine,  but  inferior  to  Experiment  I. 

Exp.  VII.     Clear,  odor  peculiar,  flavor  good. 

Exp.  IX.     Clear,  a  little  better  than  Experiment  VII. 

Exp.  VI  and  Via.  Nearly  clear,  contain  a  small  amount  of  sugar. 
Good,  full-bodied  wines  of  somewhat  Sauterne  type. 

Exp.  VIII.  Tastes  flat,  but  otherwise  a  fair  wine  of  neutral  Sauterne 
type. 

Order  of  merit  of  the  red  wines:  I,  III,  IX,  VII,  II;  of  the  white: 
VI,  Via,  VIII. 

The  analyses  of  the  wines  made  on  December  1,  1905,  by  Prof. 
George  E.  Colby,  are  given  in  the  following  table: 


TABLE  II. 

Analyses  of  Experiment  Wines  from  Fresno. 


December  1,  1905. 


Exp. 
I. 


Exp. 
II. 


Exp. 
III. 


Exp. 
VI 


Exp. 
Via. 


Exp. 
VII. 


Exp. 
IX. 


Exp. 
VIII. 


Specific  gravity... 

Alcohol,  per  cent  by  volatile 

Alcohol,  grams  per  100  cc 

"Extract,"  grams  per  100 cc 

Ash,  grams  per  100  cc 

Acidity,  total,  as  tartaric;    grams 

per  100  cc 

Acidity,  fixed,  as  tartaric;   grams 

per  100  cc 

Acidity,  volatile,  as  acetic;  grams 

per  100  cc 

Sugar,  total,  grams  per  100  cc 

Tannin 


.9935 
13.80 
10.95 
3.02 

.37 

.457 
.324 
.108 


.292 


.9955 
12.30 
9.7G 
3.10 

.38 

.397 

.285 

.090 
.200 
.160 


.9970 
12.50 
9.92 
3.25 

.45 

.442 

.300 

.114 
.300 
,240 


.9900 
13.25 
10.51 
2.19 

.25 

.390 
.300 
.072 


.9925 
14.50 
11.51 
2.80 

.37 

.337 

.292 

.036 
.300 


.9980 
11.70 
9  29 
3.30 

.57 

.375 

.300 

.060 
.300 
.280 


.9930 
15.10 
11.98 
2.60 

.41 

.315 
.232 
.066 


.9910 
12.60 
10.00 
2.07 

.33 

.375 
.315 

.048 


.260 


A  puncheon  of  each  of  the  experiment  wines  was  kept  separate  and 
left  at  the  cellar  where  they  were  made.  They  were  tasted  on  January 
1,  1906.  The  wines  made  by  the  new  method,  I  and  IX,  were  bright, 
dry,  clean-tasting,  and  of  good  flavor.  The  wines  made  in  the  ordinary 
way,  III  and  VII,  were  dry  and  clean-tasting,  clear  but  not  bright. 
The  main  differences  to  be  perceived  in  the  wines  were  that  those  made 
by  the  new  method  were  brighter  and  more  astringent  than  the  others. 

The  white  wines  were  all  in  excellent  condition,  and,  on  the  whole, 
surprisingly  good  wines  for  the  district  and  the  conditions  in  which 
they  were  made.     The  Burger  was  rather  flat  and  lacking  in  acid. 


28 


UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 


COLOR-CHANGES    IN    THE    RED    WINES. 

The  record  of  the  color-changes  in  the  various  red  wines  is  shown  in 
the  following  table.     The  same  record  is  shown  graphically  in  Pig.  11. 

TABLE  III. 
Color  of  Experiment   Wines. 


Exp.  I. 


Exp.  II. 


Before  fermentation '•    2VR,65.6    

After  fermentation |    3VR,  27.5  R,13.1 

3    months' fermentation : 3R+Y,   7.5 

4i  months'  fermentation 3VR,  16.2    3R+Y,  5.3 


Exp.  III.         Exp.  VII. 


Loss  of  color  in  3    months. 
Loss  of  color  in  Ah  months 


41°/ 


43% 
60  I 


5VR,  18.7 

5VR,  13.4 

R,  10.2 

28% 

45/ 


COLOR 
Remaining      <xt    ^k  Months 


2VR,  20.3 
2R,  13.0 
1R,    9.7 

36% 

?V9  '/ 


Lose 


Exp.  IX. 


1VR,  53.4 

22.4 

4VR.  10.6 

4VR,  17.0 

12 
24  ' 


/// 


VII 


16 A   ^S9°/0  of-0rir„i\  zy.s 


/y.o  =  y6yQ  of  oTTpZi^tZ 


b$%. 


10. 1    =SS%    of    Ordinal    j8.) 


SV/o 


9.)  =^87o    o}  Ordinal   20.3 


60% 


%  U  A 


B 


S.S  =  ±0°/o   of  Original  13.1 

FIG.  11.    Color  op  the  Red  Experiment  Wines. 

A.  Color  extracted  by  heating  before  fermentation. 

B.  Color  extracted  in  the  ordinary  way  by  fermentation. 
Shaded  Portion  =  Color  remaining  January  15,  1906. 

Clear  Portion  =  The  amount  of  the  original  color  lost. 

The  sum  of  the  above  is  the  amount  of  color  in  the  wine  when  it  was  taken 
from  the  fermenting  vats  to  the  storage  casks. 

Figure  11  shows  graphically  two  very  important  points  in  favor  of 
the  new  method:  First,  the  color  extracted  by  heating  before  fermenta- 
tion is  as  high  or  higher  than  that  obtained  by  the  usual  method;  and 
second,  that  it  is  more  stable.  Leaving  out  the  wine  of  Experiment  II, 
which  was  made  from  unripe  grapes  and  was  therefore  abnormal,  we 
find  that  the  average  loss  of  color  of  the  heated  wines  in  4-|  months  was 
32.5%,  while  that  of  the  ordinary  wines  in  the  same  period  was  48.5%. 
Experiment  II  was  cloudy  and  of  poor  quality. 


A  NEW  METHOD  OF  MAKING  DRY  RED  WINE.  29 

CONCLUSIONS. 

The  most  important  conclusion  to  be  drawn  from  these  experiments 
is  that  sound  dry  wine  of  fair  quality  can  be  produced  in  the  upper 
San  Joaquin  Valley  and  similar  regions  from  the  varieties  of  grapes 
growing  there,  simply  by  ordinary  attention  to  cleanliness,  the  steriliza- 
tion of  cooperage,  and  more  than  ordinary  attention  to  the  control  of 
temperature. 

For  white  wines  a  thorough  preliminary  defecation  of  the  must  by 
means  of  sulfur  fumes  and  the  use  of  pure  yeast  or  yeast  starters  is 
advisable. 

For  red  wines  some"  form  of  cooling  machine  is  essential,  and  the 
temperature  of  the  fermenting  wine  should  never  exceed  95°  F.,  and  if 
possible  should  be  kept  below  92°  F.  This  can  be  easily  and  perfectly 
done  by  means  of  the  cooling  machine  described  in  Bulletin  No.  174. 

The  grapes  both  for  white  and  red  wines  should  be  thoroughly  ripe. 
Ripeness  must  be  determined  by  the  flavor  and  appearance  of  the  grapes 
more  than  by  the  amount  of  sugar  they  contain.  We  can  not  hope  to 
get  the  best  results  from  imperfectly  ripe  grapes  even  if  they  contain 
22%  of  sugar.  Some  varieties  in  the  climate  of  the  San  Joaquin  Valley 
are  not  perfectly  mature  for  wine-making  purposes  until  they  contain 
25%  of  sugar  or  more.  Better  results  are  to  be  obtained  by  diluting 
and,  if  necessary,  adding  tartaric  or  citric  acid  to  over-ripe  grapes  in 
this  region  than  by  attempting  to  make  wine  from  under-ripe  grapes 
which  have  not  developed  the  color,  body,  and  flavor  necessary  for  the 
production  of  good  wine. 

Finally,  the  claims  made  in  Bulletin  No.  167  for  the  new  method  of 
wine-making  have  been  abundantly  verified  by  these  experiments.  The 
preliminary  extraction  of  color,  tannin,  and  body  by  means  of  heating 
before  fermentation  has  utilized  more  perfectly  than  any  other  method 
tested,  all  the  good  qualities  of  the  grapes  and  remedied  more  completely 
the  bad  qualities.  The  wines  made  by  this  method  have  shown  better 
color  and  flavor,  have  developed  and  kept  better,  and  have  in  every 
Avay  shown  themselves  superior  to  the  others.  The  only  thing  remaining 
to  be  tested  regarding  it  is  the  cost  when  carried  out  on  a  large  scale. 
For  this  purpose  a  plan  of  a  cellar  suitable  for  the  use  of  this  method, 
and  the  mode  of  operation  with  this  plan,  are  given.  While  the  method 
could  be  adapted  to  any  cellar  without  changing  the  vats  or  casks  at 
present  in  use,  it  would  be  much  simpler  and  more  easily  managed  in  a 
cellar  specially  constructed  for  the  purpose. 

The  plan  as  given  provides  only  for  the  manufacture  of  dry  red  wine. 
The  addition  of  some  defecating  vats  would  make  it  equally  adapted  to 
the  making  of  dry  white  wine.  The  manufacture  of  sweet  wines  would 
be  better  done  in  a  separate  crushing  and  fermenting  room  adjoining, 
though  it   could  be  done  with  the  same  machinery.     It  is  at  present 


30  UNIVERSITY  OP  CALIFORNIA — EXPERIMENT  STATION. 

doubtful  if  the  heating  method  could  be  adapted  to  the  manufacture  of 
port  wine.  The  experiments  at  present  indicate  that  too  much  tannin 
would  be  extracted  for  the  best  port.  It  might  be  possible  to  modify 
the  method  so  as  to  make  it  applicable  to  this  purpose,  but  at  present 
this  seems  hardly  necessary,  and  the  improvements  in  the  manufacture 
of  port  will  probably  lie  in  the  direction  of  cool  fermentations  and  long 
maceration  of  the  pomace. 

PLAN  OF  FERMENTING  ROOM  TO  WORK  50  TONS  OF  RED  GRAPES  PEP,  DAY. 

Explanation  of  Figures  12  and  13. 

Fifty  tons  per  day  =  11,000  gallons  of  crushed  and  stemmed  grapes. 
Fifty  tons  per  day  =8,300  gallons  of  wine  =  250,000  gallons  per  season  of  thirty  days. 
(By  working  continuously  400,000  gallons  per  season  could  be  handled  with  the  same 
installation.) 

H.  Four  extracting  vats,  12  feet  by  12  feet  by  12  feet;  capacity,  13,000 
gallons.  (11,000  gallons  will  fill  them  to  within  19  inches  of  the 
top.) 

D.  Two  drainage  vats,  12  feet  by  12  feet  by  6  feet;  capacity,  6,500 

gallons. 

F.  Six  fermenting  vats,  20  feet  by  10  feet  by  6  feet  6  inches;  capacity, 
9,000  gallons.  (8,500  gallons  will  fill  them  to  within  10  inches 
of  the  top.) 

W.    Two  pump  wells  to  hold  250  gallons. 

E.  Gomot  heater  to  heat  1,000  gallons  of  must  from  70°  to  150°  F.  in 

one  hour. 

C.  Cooler  consisting  of  240  feet  of  1^-inch  copper  pipe  and  3-inch 
No.  10  canvas  hose.  (Will  cool  1,000  gallons  of  must  from  125° 
to  80°  F.  in  one  hour  with  1,000  gallons  of  water  at  70°  F.) 

P.     Two  pumps  to  handle  1,500  gallons  per  hour  each. 

K.  Two  cooling  coils  consisting  of  80  feet  of  1-inch  copper  tubing 
(Maximum  cooling  effect  needed,  allowing  50%  for  cooling  by 
radiation  (See  Bulletin  No.  174,  p.  18),  requires  125  gallons  of 
water  at  70°  F.  per  hour  for  72  hours  for  each  vat.  This  equals 
9,000  gallons  for  each  vat  or  each  dav.  This  will  keep  the  wine 
below  92°  F.) 

T.  Carrier  for  crushed  grapes. 

S.  Carrier  and  strainer  for  crushed  grapes. 

L.  Strainer  at  bottom  of  heating  vat. 

R.  Crushing  platform. 

M.  Must  sump  to  receive  must  from  strainer  S. 

Y.  Carrier  for  extracted  pomace. 

b.  Pipe  leading  from  heater  to  heating  vats. 

a.  Pipe  leading  from  well  of  strainer  to  drainage  vats. 

o.  Manholes  for  removal  of  extracted  pomace. 

e.  Pipe  for  conducting  heated  must  to  pump  well. 

r.  Pipe  for  conducting  cold  must  into  drainage  vats. 


A  NEW  METHOD  OP  MAKING  DRY  RED  WINE. 


31 


Method  of  Operation. — 1.    The  grapes  are  crushed  and  stemmed  in 
the  ordinary  manner  on   the   crushing   platform   (R).     A  solution   of 


potassium  meta-bisulfite  is  gradually  added  to  the  crushed  grapes  as 
they  pass  from  the  crusher.     The  solution  is  made  by  dissolving  80 


32  UNIVERSITY  OF  CALIFORNIA— EXPERIMENT  STATION. 

pounds  of  the  salt  in  100  gallons  of  water,  and  is  used  at  the  rate  of 
one  gallon  to  everj^  ton  of  crushed  grapes.  This  is  equivalent  to  .2  per 
mil.  of  SO*,  and  is  sufficient  to  prevent  fermentation  until  the  extrac- 
tion can  be  accomplished,  and  helps  to  dissolve  the  color  of  the  skins, 
and  to  prevent  the  must  from  becoming  oxidized. 

2.  The  crushed  grapes  are  carried  by  an  ordinary  drag-carrier  up  the 
strainer  (S)  and  along  the  flume  (T)  to  the  extraction  vat  which  is 
being  used.  The  strainer  (S)  is  similar  to  the  usual  box  flume  used  in 
wineries,  except  that  it  is  provided  with  a  false  bottom  consisting  of 
longitudinal  slats,  which  permit  a  large  portion  of  the  must  to  run 
back  into  the  must  sump  (M). 

3.  The  must  is  then  allowed  to  run  from  M  and  from  the  extraction 
vat  into  one  of  the  drainage  vats  (D). 

4.  As  soon  as  the  drainage  vat  is  nearly  full,  or  any  time  within 
twelve  hours,  the  must  is  passed  through  the  Gomot  heater  (E)  and 
pumped  back  on  to  the  top  of  the  grape  skins  in  the  extraction  vat. 
The  opening  (r)  at  the  bottom  of  the  extraction  vat  is  meanwhile  left 
open  so  that  the  hot  must  entering  at  the  top  will  drive  out  the  cold 
must  at  the  bottom  into  the  drainage  vat. 

5.  As  soon  as  the  must,  flowing  from  the  extraction  vat  into  the  drain- 
age vat,  shows  a  rise  in  temperature  the  heater  is  connected  with  the 
opening  (r)  at  the  bottom  of  the  extraction  vat.  The  stream  of  hot  must 
now  enters  the  extraction  vat  from  the  bottom  below  the  strainer  (L), 
and  being  hotter  and  therefore  lighter  than  the  rest  of  the  must  in  the 
vat  will  tend  to  rise  and  thus  to  equalize  the  temperature  in  all  parts 
of  the  vat  of  crushed  grapes.  In  this  way  the  skins  will  all  be  thoroughly 
heated,  and  the  extraction  completed  without  stirring  or  using  the 
heater  on  half-heated  must,  which  would  result  in  a  loss  of  efficiency. 

The  temperature  to  which  it  will  be  necessary  to  raise  the  must  as  it 
passes  through  the  heater  will  depend  on  the  initial  temperature  of  the 
grapes  and  on  the  amount  of  must  which  it  is  possible  to  separate.  By 
proceeding  in  the  way  described,  it  would  undoubtedly  be  possible  to 
separate  an  amount  of  must  equal  to  two-thirds  the  volume  of  the  grapes, 
or  about  145  gallons  per  ton.  If  the  temperature  of  the  grapes  therefore 
was  70°  F.,  and  the  must  was  passed  through  the  heater  at  a  temperature 
of  153c  F.,  the  whole  contents  of  the  extracting  vat  would  be  raised 
to  125°  F.,  which  is  the  temperature  required. 

6.  If  necessary  to  hasten  or  complete  extraction,  the  must  should  be 
allowed  to  run  into  the  pump  well  (W)  and  returned  to  the  top  of  the 
pomace  in  the  extracting  vat. 

7.  It  is  then  allowed  to  stand  for  sufficient  time  to  extract  the  neces- 
sary color  and  tannin.  This  time  will  differ  according  to  the  kind  of 
grape,  the  kind  of  wine  desired,  and  the  temperature  of  extraction.  If 
the  temperature  of  125°  F.  is  used  the  time  of  extraction  will  be  from 


A   NEW  METHOD  OF  MAKING  DRY  RED  WINE. 


33 


four  to  eight  hours.     With  higher  temperatures  it  will  be  less,  with  lower 

more.     Lower  temperatures  and  long  maceration  will  give  more  tannin; 

higher      temperatures      with  | 

shorter  maceration  will    give 

less  tannin  for  a  given  amount 

of  color.    This  is  due  probably 

to   the    extraction    of   tannin 

from  the    seeds   which    takes 

place  after  long  contact  with 

the  hot  must. 

8.  As  soon  as  the  extraction 
is  complete,  the  hot  must, 
containing  color  and  tannin, 
is  allowed  to  run  into  the 
pump  well  (W)  and  pumped 
through  the  cooler  (C)  into  a 
fermenting  vat  (F).  The  tem- 
perature of  the  must  when  it 
reaches  the  fermenting  vat 
should  be  about  80°  F.  The 
must  as  it  passes  from  the 
cooler  (C)  into  the  fermenting 
vat  should  be  allowed  to  fall 
through  the  air  in  order  to 
aerate  it  thoroughly.  This  is 
essential  for  a  quick  and 
thorough   fermentation. 

9.  As  the  fermenting  vat  is 
being  filled,  about  75  gallons 
of  yeast  should  be  added. 
This  yeast  may  be  prepared 
as  described  on  page  13,  or  it 
may  be  simply  some  ferment- 
ing wine  taken  from  one  of 
the  other  vats  that  is  in  full 
fermentation.  The  use  of 
pure  yeast  as  described  is  pref- 
erable, as  the  actual  amount 
of  yeast  added  is  more  easily 
controlled.  If  we  use  75  gal- 
lons of  fermenting  wine  from 
another  vat  the  amount  of 
yeast  in  it,  and  still  more  the 
character  of  it,  will  vary  very 

bul.   177  —  3 


34  UNIVERSITY  OF  CALIFORNIA  — EXPERIMENT  STATION. 

much  according  to  the  stage  of  fermentation  at  which  the  wine  has 
arrived.  Yeast  prepared  by  the  method  indicated  will  always  be  in  full 
vigor  and  the  number  of  active  cells  present  will  be  fairly  constant. 
This  will  cause  the  fermentations  to  be  more  regular  and  simplify  the 
control  of  temperature. 

10.  As  soon  as  the  must  ceases  to  run  from  the  extraction  vat  the 
gate  (())  is  opened  and  the  pomace  shoveled  out  to  the  carrier  (Y), 
which  takes  it  to  a  continuous  press.  The  must  from  the  press  is  mixed 
with  that  already  in  the  vat.  It  will  probably  be  unnecessary  to  cool 
the  press  must. 

11.  Fermentation  will  start  immediately,  and  as  soon  as  the  temper- 
ature rises  to  90°  F.  one  of  the  cooling  coils  (K)  should  be  lowered  into 
the  must  a  couple  of  inches  below  the  surface  and  water  run  through  it. 
No  stirring  of  the  fermenting  liquid  will  be  necessary,  as  the  heating 
must  rises  to  the  surface,  is  cooled  on  contact  with  the  copper  coil,  and 
sinks  again.  This  keeps  up  a  constant  circulation.  A  moderate  aera- 
tion should  be  given  once  a  day,  either  b}r  pumping-over  or  by  means 
of  an  air  compressor.  Unless  this  is  done  the  fermentation  will  be 
inconveniently  slow.  If  too  much  aeration  is  given  the  quality  and 
color  of  the  wine  will  be  injured. 

12.  At  the  end  of  three  days  the  wine  should  not  contain  more  than 
1%  or  2%  of  sugar  and  should  mark  0  on  the  saccharometer.  It  should 
then  be  transferred  to  the  storage  cellar,  being  given  a  thorough  aeration 
in  the  transfer. 

Figure  14  shows  the  sequence  in  which  the  various  vats  shown  in 
Figs.  12  and  13  would  have  to  be  used.     Each  circle  represents  a  vat. 

Each  column  represents  a  day,  and  shows  the  condition  of  all  the 
vats  on  the  day  indicated  at  the  head  of  the  column. 

Each  horizontal  file  shows  the  condition  of  a  vat  on  the  various  da}Ts 
indicated. 

Each  heavy  line  represents  the  course  of  the  must  handled  on  a  single 
day.  For  example,  on  the  first  day  the  must  from  the  crusher  falls 
into  extraction  vat  H  and  runs  into  drainage  vat  D.  On  the  second 
day  it  is  taken  from  D,  passed  through  the  heater  and  back  into  H. 
On  the  third  day  the  must,  now  containing  color  and  tannin,  is  taken 
from  H  and  passed  through  the  cooler  into  fermenting  vat  F.  It  stays 
in  F  during  the  fourth,  fifth,  and  sixth  days,  and  is  transferred  to  a 
storage  cask  on  the  seventh.  When  everything  is  in  full  running,  as 
on  the  seventh  day,  and  as  indicated  in  the  figure,  one  of  the  extraction 
vats  (H^)  is  being  filled  from  the  crusher.  The  cold  must  from  Hj  is 
draining  into  one  of  the  drainage  vats  (D).  Another  extraction  vat 
(H2)  is  being  heated  by  the  must  from  the  other  drainage  vat  (T)1). 
Another  extraction  vat  (H)  is  being  drawn  off  and  the  hot  red  must 


DAYS 


FIG.  14.     Diagram  showing  order  in  which  vats  must  be  used. 


36  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

passed  through  the  cooler  into  one  of  the  fermenting  vats  (F5).  The 
fourth  extraction  vat  (H3)  is  empty  and  being  prepared  for  filling  on 
the  following  day.  Three  of  the  fermenting  vats  (F2,  F3  and  F4)  are 
full  of  fermenting  wine,  and  one  (Fj)  is  being  emptied  of  fermented 
wine.  The  sixth  fermenting  vat  (F6)  is  empty  and  ready  for  filling 
the  following  day. 

The  whole  process  could  be  very  much  shortened  if  needed.  The 
extraction,  instead  of  taking  seventy-two  hours  as  indicated,  could  be 
better  done  in  thirty-six  hours,  and  the  must  need  not  stay  in  the 
fermenting  vats,  from  the  commencement  of  filling  to  the  end  of  empty- 
ing, more  than  four  days.  In  this  way  the  output  could  be  increased 
from  8,300  gallons  per  day  of  twenty-four  hours  to  over  13,000  gallons; 
and  with  the  addition  of  another  fermenting  vat  and  a  corresponding 
increase  of  the  cooling  apparatus  to  15,000  gallons  per  day. 


ACKNOWLEDGMENTS. 

The  successful  carrying  out  of  the  foregoing  experiments  was  rendered 
possible  by  the  cooperation  of  members  and  employes  of  the  California 
Wine  Association,  who  provided  all  the  necessary  grapes  and  cellar 
facilities  and  assisted  materially  by  their  interest  and  cooperation. 

Our  thanks  are  also  especially  due  to  Messrs.  T.  R.  Meakin  and  son, 
whose  advice  and  skill  in  constructing  the  needful  apparatus  very  much 
facilitated  every  stage  of  the  work;  and  to  Mr.  B.  J.  Wingfield,  who 
carefully  and  skillfully  attended  to  all  the  details  of  the  experiments. 


STATION  PUBLICATIONS  AVAILABLE  FOR   DISTRIBUTION. 


REPORTS. 


1896.  Report    of    the    Viticultural    Work    during    the   seasons    1887-93,    with    data 

regarding  the  Vintages  of  1894-95. 

1897.  Resistant    Vines,    their    Selection,    Adaptation,    and    Grafting.      Appendix    to 

Viticultural  Report  for  1896. 

1898.  Partial   Report  of  Work  of  Agricultural   Experiment  Station  for  the  years 

1895-96  and  1896-97. 
1900.     Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for  1901-1903. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-1904. 

BULLETINS. 

Reprint.  Endurance  of  Drought  in  Soils  of  the  Arid  Region. 

No.  128.  Nature,  Value,  and  Utilization  of  Alkali  Lands,  and  Tolerance  of  Alkali. 
(Revised  and  Reprint,  1905.) 

131.  The  Phylloxera  of  the  Vine. 

133.  Tolerance  of  Alkali  by  Various  Cultures. 

135.  The  Potato-Worm  in  California. 

137.  Pickling   Ripe  and   Green   Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange  and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Roble.^. 

142.  Grasshoppers  in  California. 

143.  California  Peach-Tree  Borer. 

144.  The  Peach-Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their  Hybrids. 

149.  California  Sugar  Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl  Cholera. 

157.  Commercial  Fertilizers. 

158.  California  Olive  Oil ;   its  Manufacture. 

159.  Contribution  to  the  Study  of  Fermentation. 

160.  The  Hop  Aphis. 

161.  Tuberculosis  in  Fowls.      (Reprint.) 

162.  Commercial  Fertilizers.      (Dec.  1,  1904.) 

163.  Pear  Scab. 

164.  Poultry  Feeding  and  Proprietary  Foods.      (Reprint.) 

165.  Asparagus  and  Asparagus  Rust  in  California. 

166.  Spraying  for  Scale  Insects. 

167.  Manufacture  of  Dry  Wines  in  Hot  Countries. 

168.  Observations  on  Some  Vine  Diseases  in  Sonoma  County. 

169.  Tolerance  of  the  Sugar  Beet  for  Alkali. 

170.  Studies  in  Grasshopper  Control. 

171.  Commercial  Fertilizers.      (June  30,  1905.) 

172.  Further  Experience  in  Asparagus  Rust  Control. 

173.  Commercial  Fertilizers.      (December,  1905.) 

174.  A    New   Wine-Cooling  Machine. 

175.  Tomato  Diseases  in  California. 

176.  Sugar  Beets  in  the  San  Joaquin  Valley. 

CIRCULARS. 

No.  1.  Texas  Fever.  No.  13.     The  Culture  of  the  Sugar  Beet. 

2.  Blackleg.  14.     Practical    Suggestions    for   Cod- 

3.  Hog  Cholera.  ling-Moth      Control      in      the 

4.  Anthrax.  Pajaro  Valley. 

5.  Contagious  Abortion  in  Cows.  15.  Recent  Problems  in  Agriculture. 
7.  Remedies  for  Insects.  What  a  University  Farm  is 
9.  Asparagus  Rust.  For. 

10.  Reading    Course    in    Economic  16.     Notes  on   Seed-Wheat. 

Entomology.  17.     Why     Agriculture     Should     be 

11.  Fumigation  Practice.  Taught  in  the  Public  Schools. 

12.  Silk  Culture.  18.     Caterpillars  on  Oaks. 

Copies  may  be  had  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


